Energy Pyramid/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby A TV screen shows schools of fish swimming in deep waters. A voice ominously narrates. NARRATOR: It's that time of year again. The time when fear leaves the ocean and heads into your living room. Nature's deadliest killing machines as you've never seen them before. A huge shark swims from the deep waters and hunts a zebra and rabbit on land. It holds up a knife and fork to dine on them. NARRATOR: It's shark month. And this time it's personal. The shark is dressed as a pirate aboard a pirate ship. It makes a blindfolded man walk the plank. Tim and Moby are watching the television. Moby looks worried. MOBY: Beep. TIM: I don't think you have anything to worry about. Some of that footage seems a little fake. Moby hands Tim a letter. Tim reads from the typed letter. TIM: Dear Tim and Moby, what is an energy pyramid? Your friend, Nicole. MOBY: Beep. Moby is sitting on top of an ancient Egyptian pyramid. TIM: Uh, I don't think she means that pyramid. The energy pyramid is a model for how energy spreads through an ecosystem. An image shows a triangle. TIM: You remember food chains, right? MOBY: Beep. Moby holds up a sausage chain. TIM: Why are you being so literal today? Okay, the food chain describes how organisms in an ecosystem are linked together by what they eat. At the bottom are producers. On land, that includes plants, from moss and grass to shrubs and trees. An image shows a meadow, and close-ups show the producers Tim describes. TIM: The producers are eaten by primary consumers. These are herbivores, or plant-eaters. An image shows a rabbit and grasshopper as herbivores in the meadow. TIM: In turn, the primary consumers are eaten by secondary consumers. These are carnivores, or meat-eaters. A snake and raccoon appear in the meadow to represent carnivores that will eat the rabbit and grasshopper. TIM: This continues until you reach the animals at the top of the food chain, which have no natural enemies. An animation shows the snake trying to get away from a swooping eagle that pounces on it. MOBY: Beep. An animation shows the raccoon pleading with a shark not to eat it. TIM: Uh, sharks are at the top of the marine food chain. Bears might be a better example here. A bear smacks the shark away and eyes the raccoon hungrily. TIM: Meanwhile, decomposers, like bacteria and fungi, break down dead animal and plant matter. An image shows decomposers on a decaying log with a dead animal nearby. TIM: This recycles nutrients back into the ecosystem. Food chains usually combine to form food webs, made of many interconnected and overlapping chains. An image shows various plants and animals with arrows showing which ones provide food for others. Some animals are at the top and don't provide food for any other animal. Animals at the top are a raptor, a bear, and a fox. TIM: But let's back up for a sec and ask why animals eat in the first place. MOBY: Beep. TIM: Well, yes, leaves, grasshoppers, and snakes are delicious. An image shows these things on a plate. TIM: In certain cultures, I guess. A girl holds a fork and seems confused by the plate of food. TIM: But that's not it. Animals eat to gain energy. MOBY: Beep. TIM: It all starts with producers. They create all of the usable energy in an ecosystem. That's why they're called producers. Through the process of photosynthesis, they convert the sun's light energy into chemical energy, specifically, a simple sugar called glucose. Glucose is the fuel that drives all living organisms. Plants use up most of the glucose they make to grow and reproduce. But they store a little bit of it in their bodies. An animation shows a smiling flower holding a glass as it absorbs sun rays. The glass fills with an orange-colored drink that is labeled, glucose. The flower drinks most of the glucose and burps. The small amount of glucose that is left in the glass is labeled, glucose stored. TIM: So when a rabbit eats a plant, he's only getting a small fraction of the energy the plant got from the sun. The animation continues with a rabbit taking the glass from the plant. The plant disappears, and the rabbit drinks the small amount of glucose the plant left in the glass. TIM: The rabbit, in turn, uses up most of that energy to do things like breathe, keep warm, move around, and, um, make baby rabbits. Images show the rabbit sleeping in a bed, jogging, and giving flowers to a female rabbit. TIM: So if a fox comes along and eats that rabbit, he's only getting a teeny tiny fraction of the energy that was first absorbed by the plants! The animation continues with a fox taking the glass from the rabbit. The rabbit disappears, and the fox drinks a drop of glucose that's in the glass. TIM: Get it? MOBY: Beep. TIM: Right, all of the energy in an ecosystem ultimately comes from the sun! An animation shows a bright sun. TIM: And since the amount of energy decreases as it travels up the food chain, it can be represented as a pyramid. An animation shows an energy pyramid. The sun hovers in the sky above the pyramid. An axis labeled as Energy spans the width of the pyramid's base, which shows how the decreasing width of each pyramid level represents a decrease in energy. The levels from the bottom to the top are producers, herbivores, carnivores, and top predator. To illustrate the flow of energy, an arrow points from the sun to the base of the pyramid, and arrows point up from one level to the next, from producers to top predator. MOBY: Beep. TIM: In general, each level of the pyramid gets ten times less energy than the level below it. The numbers for energy for each level of the pyramid are 10,000 for producers, 1,000 for herbivores, 100 for carnivores, and 10 for top predator. TIM: So, let's say you've got a square meter of forest. Every year, the plants growing in the little patch produce 10,000 calories. That's a unit of energy. An image shows the patch of land that produces 10,000 calories. TIM: Now, let's say herbivores consume those 10,000 calories. They burn nine thousand calories and store one thousand in their bodies. Rabbits and grasshoppers appear on the patch of land. The animals and bugs are shown to burn and store the amounts Tim mentions. TIM: So for their predators, that square meter of forest produces only one 1000 calories of energy per year. That means there are gonna be way fewer snakes and raccoons than rabbits and grasshoppers. The snake and raccoon predators appear on the patch of land. The text 1,000 calories shows on the animation. TIM: See where this is going? MOBY: Beep. TIM: Right! If the carnivores eat all of the primary consumers, they'll gain 1,000 calories of energy. They'll use up 900 calories and store 100 in their bodies. So, for the top predators, that square meter of forest only yields 100 calories per year. An image places the animals providing energy for each other inside the energy pyramid. The numbers of calories they provide for each other are shown at each level of the pyramid as Tim describes. Suddenly, a shark appears as a top predator in the energy pyramid, replacing the raptor and bear that were there. TIM: Oh, come on. Sharks aren't part of the equation, here! The shark disappears and the bird and bear reappear. TIM: That's better. Anyway, since the bears and hawks have a fairly limited number of calories to live on, the ecosystem just can't support that many of them! The energy pyramid image shows that the higher the level in the energy pyramid, the fewer items or animals are in the level. The bottom level is plant life and is most abundant. TIM: So in most cases, as energy decreases up the food chain, so does biomass, the combined mass of all the organisms. The energy pyramid is shown. The label Energy/Biomass appears below it. TIM: A small meadow might support 10,000 grasshoppers, 100 snakes, and only one or two hawks. Images show the meadow and the animals as Tim describes. MOBY: Beep. TIM: Great. Now let's get back to Shark Month. I think there's a special coming up about a shark who lent out money at a very high interest… TIM: Hmm, who could that be? Tim opens the door. A shark dressed as a postal worker hands him a package. Tim brings the package to the sofa and sits with Moby. TIM: You know, there was something fishy about that guy. Category:BrainPOP Transcripts